Polyvinyl acetal resin compositions containing diglycerol tetrapropionate



Patented Oct. 15, 1940 UNITED STATES 2,218,251 POLYVINYL AOETAL RESIN COMPOSITIONS CONTAINING PIONATE DIGLYQEROL TETRAPRO- Henry B. Smith, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application December 15, 1937,

Serial No. 180,034

8 Claims. (Cl. 260-36) This invention relates to plasticcompositions, and more particularly to compositions comprising a polyvinyl acetal resin and a conditioning agent.

One object of this invention is to produce compositions of matter which may be made into permanently transparent, strong and flexible sheets or films of desired thinness which are substantially waterproof, are unaffected by ordinary 1 photographic fiuids and possess the desired properties of a support for senstitive photographic coatings. Another object of my invention is to produce compositions of matter which can be made into sheets suitable for use in laminated,

shatter-proof glass. Still another'object' is to produce compositions which can be rolled, extruded, molded or otherwise worked into relatively thick sheets and massive plastics. A further object is to produce compositions suitable for use in lacquers, artificial silk filaments, wrapping tissues and the like. Other objects will hereinafter appear.

I have discovered that diglycerol tetrapropionate is a useful conditioning agent for polyvinyl acetal resins. Not only does it serve as a plasticizer in the accepted sense of the termLincreasing the flexibility and toughness of polyvinyl acetal resin films, sheets, or other objects or masses containing it, but when used in 80 amounts of about 45 or more parts per 100 parts of certain of the polyvinyl acetal resins, namely the polyvinyl acetal resins in which a predominating proportion of the acetal groups are butyraldehyde acetal groups, it has an unusual and remarkable efiect which I may call elasticizing.

That is to say, a sheet of a polyvinyl butyraldehyde acetal resin containing about 45 or more parts of diglycerol tetrapropionate per 100 parts of resin possesses the property which, in the rubher industry, is known as nerve: namely, the property of stretching to a considerable extent when tension is exerted upon it, andreturning to its original dimensions when the tension is released. This property renders such sheets, which .I. shall call rubbery sheets, particularly useful in the manufacture of shatter-proof glass.

For the manufacture of cast films or sheets, the polyvinyl acetal resin and diglycerol tetrapropionate may be dissolved in a suitable solvent or solvent mixture, such, for instance, as acetone, methanol, acetone-methanol mixtures, ethylene chloride-methanol mixtures, etc., about 300 to 500 or more parts of the solvent or solvent mixture being used per 100 parts of the resin. From about 2 to 100 parts or more of diglycerol tetrapropionate per 100 parts of resin may be employed, depending upon the nature of the resin and the purpose for which the sheets are to be used. Suitable proportions of digylcerol tetrapropionate for any resin and any purpose. may be readily determined by experiment. For the manufacture of sheets suitable for photographic film base, .from 2 to 25 parts of diglycerol tetrapropionate per 100 parts of resin are suitable. The resin solution is cast as a sheet, solvent evaporated, and stripped from casting surface.

Sheets for use in laminated glass may be formed by casting, or may be made without the use of volatile solvent by extrusion, for example in the manner set forth in application Serial No. 147,934 of John S. Kimble and Ernest C. Blackard, filed June 12, 1937. For instance, 45 or more parts of diglycerol 'tetrapropionate and 100 parts of a polyvinyl butyraldehyde acetal resin may be mixed at room temperature or at a reduced temperature, in a suitable mixer, and the mixture may then be worked on hot rolls, in the manner described in U. S. Patent 2,048,686 of F. R. Conklin, until complete homogenization has taken place. The mass thus produced may then be extruded through an annular die, and the tube so formed slit to form a sheet.

The polyvinyl acetal resins can be prepared by reacting polyvinyl alcohol with an aldehyde in the presence of an acetal condensation catalyst, e. g., a mineral acid. These resins can also be prepared by simultaneously de-esterifyin'g a polyvinyl aliphatic ester and reacting the de-esterification product with an aldehyde in the presence of a de-esterlfying catalyst and acetal condensation catalyst. Mineral acids are catalysts for both de-esterification and acetal formation. Among the polyvinyl acetal resins with which diglycerol tetrapropionate is useful may be mentioned, as illustrative examples, the polyvinyl formaldehyde acetal resins, the polyvinyl acetaldehyde acetal resins, the polyvinyl formaldehyde acetaldehyde mixed acetal resins, the polyvinyl butyraldehyde acetal resins, and the polyvinyl butyraldehyde acetaldehyde mixed acetal resins.

Examples of the preparation of polyvinyl formaldehyde acetal resins may be found in U. S. Patent 1,955,068, Examples 1, 4 and 5; inU. S. Patent 2,036,092, Examples 1, 2, 3, 7 and 8; in British Patent 454,691, Examples 1, 2, 3, 4, 5, 6 and 7; in British Patent 404,279, Example 3; and in British Patent 436,072, Examples 1, 2, 3, 4, 5, 6 and 7. A further example of'thepreparation of a polyvinyl formaldehyde acetal resin is as follows:

whose molar" solution (86.08 g. per liter) in benzene was 45 centipoises, was dissolved in 75 lbs. of 70% acetic acid. To this solution were added 56 grams of hydroxylamine hydrochloride, for stabilizing the resin, 5.25 lbs. of trioxymethylene, and 6.25 lbs. of 35% H01. The reaction mixture was allowed to stand for 5 days at 40 C., after which it was diluted with acetic acid. The resin was precipitated by pouring into cold water, washed, and dried. Analysis showed the resin to have an acetate group content equivalent to-10.6%. by weight oi. polyvinyl acetate and a hydroxyl group content equivalent to 7.1% by weight of polyvinyl-alcohol. The stabilization of polyvinyl acetal resins by hydroxylamine is claimed in the application of Joseph B. Hale, Serial No. 149,916, filed June 23, 1937.

Examples of the preparation of polyvinyl acetaldehyde acetal resins may be found in U. S. Patent 2,044,730, Example 1; U. S. Patent 1,955,068, Example 2; U. S. Patent 2,036,092,Ex-

amples 4, 5 and 6; British Patent 466,598, Ex-

amples 1, 2, 3, 4 and 7; British Patent 404,279, Examples 1, 2, 4, 5, 6, 7 and 8; U. S. Patent 1,990,399; and French Patent 808,578, Examples 1, 2 and 3.

An additional example of the preparation of a polyvinyl acetaldehyde acetal resin is as follows: 100 lbs. of polyvinyl acetate, the viscosity of whose molar solution in benzene was 45 centipoises, was dissolved in 300 lbs. of 95% ethyl alcohol. To this solution were added lbs, of paraldehyde and 25 lbs. of HCl. The reaction mixture was allowed to stand for 4 days at C., after which it was diluted with ethyl alcohol,

and the resin precipitatedby pouring into cold water, washed and dried. Analysis showed the resin to have an acetate group content equivalent to 2.1% by weight of polyvinyl acetate and a hydroxyl group content equivalent to 12.9% by weight of polyvinyl alcohol.

Examples of the preparation of polyvinyl formaldehyde acetaldehyde mixed acetal resins may be found in British Patent 430,136, Examples 1, 2, 3, 4, 5 and 6; British Patent 445,565, Example 2; British Patent 465,873, Examples 1, 2, 3, 4, 5 and 6; French Patent 808,586, Examples 1, 2, 3, 4,5, 6, 12, 13, 14, 15, 16, 17, 18 and 19.

Additional examples of the preparation of polyvinyl formaldehydeacetaldehyde mixed acetal resins are given in the application of Ralph H.

Talbot, Serial No. 85,960, filed June 18, 1936, as

follows:

Example 1 100 parts (1.16 mol. calculated as monomeric vinyl acetate) of a polyvinyl acetate centipoises), 100 parts of ethyl alcohol, 180 parts of ethyl acetate, 34 parts (.77 mol. as monomeric acetaldehyde) of paracetaldehyde and 5.8 parts (.196 mol. as monomeric formaldehyde) of paraformaldehyde were placed in an enameled vessel and brought into solution by stirring. When solution-was complete, 10 parts of sulfuric acid (sp. g. 1.84) in 10 parts of water were added, and the mixture stirred. The mixture was maintained at a temperature of 40 C. for 144 hours. The contents of the vessel were then diluted with about two and a half volumes of acetone, and the mixture precipitated into water. The precipitated resin was washed free from impurities by repeated changes of cold water, and dried. The resin, when analyzed, gave a hydroxyl group content {5 lbs. of polyvinyl acetate, the viscosity of equivalent to about 6.4 percent by weight of polyvinyl alcohol, an acetate group content equivalent I to about 4.0 percent'by weight of polyvinyl acetate, 2. formaldehyde acetal group content equivalent to about 15.9 percent by weight of polyvinyl formaldehyde acetal and an acetaldehyde acetal group content equivalent to about 73.9 percent by weight of polyvinyl acetaldehyde acetal. The

polyvinyl acetal portion of the resin was therefore made up of about 19.7 percent by moles of polyvinyl formaldehyde acetal and about 80.3 percent by moles of polyvinyl acetaldehyde acetal. The resin was soluble in acetone to an extent which permitted coating a film or sheet from the resin.

"Example 2 parts (.58 mol. as monomer) of polyvinyl acetate (45 centipoises), 50 parts of ethyl alcohol, 90 parts of ethyl acetate, 17 parts (.385 mol. as monomer) of paracetaldehyde, 2.9 parts (.098 mol, as monomer) of paraformaldehyde, 5 parts of sulfuric acid and 5 parts of water'were treated as in Example 1 for 161 hours. The well washed and dried resin gave upon analysis a hydroxyl group contentequivalent to about 9.6% by weight of polyvinyl alcohol, an acetate group content equivalent to about 4.1% by weight of polyvinyl acetate, a formaldehyde acetal group content equivalent to about 13.9 percent by weight of polyvinyl formaldehyde acetal, and an acetaldehyde acetal group content equivalent to about 69.9, percent of polyvinyl acetaldehyde acetal.

' The polyvinyl acetal portion of the resin was therefore made up of about 18.5 percent by moles of polyvinyl formaldehyde acetal and 81.5 percent by moles of polyvinyl acetaldehyde acetal. The resin was soluble in acetone to an extent which permitted coating'a film or sheet from the resin.

"Example 3 .hours, agitating throughout. At this point, 266.4

parts (6.05 mol. as monomer) of paracetaldehyde were added and heating at about C. with agitation was continued for a further period of twenty hours. The contents of the reaction vessel were neutralized with ammonium hydroxide and diluted with water precipitating the resin. as a cake. The cake was cut into small pieces and repeatedly washed with hot water until the resin was free from solvents, salts and other impurities. The resin, upon analysis, showed a hydroxyl group content equivalent to about 10.1 percent by weight of polyvinyl alcohol, an acetate group content equivalent to about 3.2 percent by weight of polyvinyl acetate, the remainder of the weight of the resin being polyvinyl acetal. The polyvinyl acetal portion of the resin was made up of about 80 percent by moles of polyvinyl acetaldehyde acetal and about 20 percent by moles of polyvinyl formaldehyde acetal. The resin was not quite solution in acetone, but could be made to dissolve by admixing small amounts of other solvents, such as alcohols. with the acetone.

Examples of the preparation of polyvinyl butyraldehyde acetal resins may be round in U. S. Patent 2,044,730, Examples 2, and 6; British Patent 466,598, Example 5; French Patent 813,- 303, Example 1; French Patent 813,514, Examples 1, 2, 3 and 4; and British Patent 459,878, Examples 1, 2, 5, 6, 7, 8, 9 and 10.

An additional example of the preparation of a polyvinyl butyraldehyde acetal resin is as follows:

23.6 lbs. of polyvinyl acetate, the viscosity of whose molar solution in benzene was 45 centipoises, was dissolved in 56.5 lbs. of 95% ethyl alcohol. To this solution was added 7.9 lbs. of butyraldehyde and 5.9 lbs. of 35% HCl. The reaction mixture was allowed to stand for 4 days at 40 C., after which it was diluted with ethyl a1- cohol and acetic acid, and the resin precipitated by pouring into cold water, washed, and dried. Analysis showed the resin to have an acetate group content equivalent to 3.1% by weight of polyvinyl acetate and a hydroxyl group content equivalent to 16.3% by weight of polyvinyl alcohol.

An example of the preparation of a polyvinyl b-utyraldehyde acetaldehyde mixed acetal resin is given in French Patent 813,303, Example 2.

What I claim as my invention and desire to be secured by Letters Patent of the United States is:

1. A composition 01. matter comprising a polyvinyl acetal resin and a diglycerol tetrapropionate as a plasticizer therefor.

2. A transparent, flexible sheet comprising 100 parts of a polyvinyl acetal resin and from 2 to 25 parts, approximately, of diglycerol tetrapropionate as a plasticizer therefor.

3. A transparent, rubbery sheet comprising 100 parts of a polyvinyl acetal resin in which a predominating proportion of the acetal groups are butyraldehyde acetal groups, and at least 45 parts, approximately, of diglycerol tetrapropionate as an elasticizer therefor.

4. A composition of matter comprising a polyvinyl acetaldehyde acetal resin and diglycerol tetrapropionate as a plasticizer therefor.

5. A transparent, flexible sheet comprising 100 parts of a polyvinyl acetaldehyde'acetal resin and from 2 to 25 parts, approximately, of diglycerol tetrapropionate as a plasticizer therefor.

6. A composition of matter comprising a polyvinyl butyraldehyde acetal resin and diglycerol tetraproplonate as a plasticizer therefor.

7. A transparent, flexible .sheet comprising 100 parts of a polyvinyl but'yraldehyde acetal resin and from 2 to 25 parts, approximately, of diglycerol tetrapropionate as a. plasticizer therefor.

8. A transparent, rubbery sheet comprising 100 parts of a polyvinyl butyraldehyde acetal resin and at least 45 parts, approximately, of diglycerol tetrapropionate as an elasticizer therefor.

HENRY B. SMITH. 

